Curious about cost of motor replacement? 4.0

[collestat]

So if you've been following my posts at all you'll know that I'm looking into either a YJ or most likely a TJ and I'm cautious with regards to miles on the engine and was just wondering...generally speaking...to go to a shop what kind of ballpark it would cost to get either a new or rebuilt 4.0 engine put in place of an old one. That and I've seen people looking to sell cheap because the engine has a knock.